Gut check: new study targets stomach woes in female athletes

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Female, cisgender, premenopausal. 2. Minimum age 18 years. 3. Regular, natural menstrual cycle (21-35 days in duration), with 9 or more consecutive periods per year, if possible documented with tracker apps, calendars, or other tools. 4. Willingness and ability to give informed consent and to understand, to participate, and to comply with the clinical study requirements. 5. Body mass index (BMI) ≥ 18.5 and \< 24.9 kg/m2 6. Agreeing to maintain lifestyle habits during the study (same dietary and physical activity habits) 7. Having a smartphone and a history of consistent tracking of training and health records via apps. 8. Having regular GI issues during exercise, preferably also during menstruation. During pre-screening, this will be assessed with a shortened GSRS questionnaire, where participants need to have had, in the month preceding pre-screening, the equivalent of at least a score of 2 in a GSRS focus area (diarrhoea, pain, indigestion). 9. No relevant self-reported abnormalities from medical history. 10. Trained athlete (trains at least 3 times per week for more than 1 hour per day and who has been involved in endurance training for at least 2 years in alignment with previous research (Pfeiffer et al., 2010). This will be evaluated by assessing training records (Strava or similar application, certificates of attendance to athletic events, club membership, etc.). 11. Access to a health-care provider, who can be contacted by the CRO, and who reside in areas with available health services. Exclusion Criteria: 1. Individuals who are pregnant, lactating, or plan to become pregnant before study end. 2. Individuals with secondary amenorrhea. 3. Individuals who use hormonal contraceptives during the last 6 months before (and during) the trial. 4. Individuals who are currently participating in another clinical trial or have participated in a trial within the last two months prior to enrolment. 5. Tobacco smokers and vapers. 6. Individuals with acute illness. 7. Individuals with a current musculoskeletal injury or one within the last month. 8. Individuals taking probiotic supplements or who have taken probiotics two weeks prior to enrolment. 9. Individuals controlling chronic diseases with treatments known to alter the intestinal microbiome or to alter GI symptoms, such as certain pain killers, antacids, proton-pump inhibitors, anti-diarrhoeal medication or supplements, and laxatives. 10. Individuals having received antibiotics treatments within three months of trial start. 11. Individuals having planned major changes in lifestyle (i.e. diet, weight loss program, exercise level, travelling) during the duration of the study. 12. Individuals who have any hypersensitivity/allergy to any of the components of the test product. 13. Individuals who have planned major elective surgery during the study period.